First, the user defines the scaffold that must be the same for all products. When drawing, hydrogens replace the reactants R. In the case below, R1 and R2 are substituted by H.

Then, the first substitution site is defined. In the case below, the R1 reactants will be connected to the atom number 3 of the scaffold.

The reactant library is uploaded and modified according to the user specifications (only single bonds are broken). In the case below, the azido reactant library is modified in order to keep the R1 group only.

Finally, the scaffold is connected to each modified reactant R. The resulting library is downloadable or subject to another reactant addition or can be evaluated/filtered by an user-defined scoring function (molecular properties and/or docking on a protein).